To give you an idea of what you can save while in the military, I got out of the Army after 8 years with $85k saved. I also saved my leave my last few years so I got out 3 months early and continued to get paid(This isn't always possible, sometimes your command will force you to use leave and some commanders will only sign off on so much terminal(end of service) leave.

I started using the GI Bill ASAP. I live about an hour outside of Boston, but go to school in the city. You get a monthly living allowance which is based on the location of your school. Since Boston is extremely expensive I get $3100 a month. I got out with a disability rating so I'm in a program called Vocational Rehab which pays the full boat on my $27k/semester tuition at a private university. I also get every single book paid for, all my nursing uniforms and supplies, plus a few hundred in school supplies each semester. When I started the VocRehab program I got a higher-end 13" MacBook Pro and printer.

My disability rating is 100% for now(got blowed up...you don't want a disability rating) which means I get another $3200/month. So as a student I have my tuition, books, and supplies covered and also make $6300 per month...tax free.